The invention relates to graphics input devices which are operated manually by a user to provide signals defining a graphical object whose image is to be displayed in a graphics system.
In the prior art, hand-operated pointing or picking devices are known. These devices are operated by a user to position a cursor on the screen of a graphical output device such as a display. The primary role of these devices is to permit a user to select a specific XY location on a display screen. Other devices, called locator devices, include the tablet, the mouse, the trackball, and the joystick. All of these devices are employed to move a screen cursor, and operate in combination with separate devices which input information relevant to the location occupied by the cursor. Most commonly, function buttons, function switches, or alpha-numeric keyboards are used for command or information entry after positioning of a cursor.
In the prior art, the drawing of graphic objects has been the province of a program entered into a graphics processor. Commonly, such an application program utilizes a bottom-up procedure for object creation, using hierarchially-arranged object components. The components map to a set of output primitives with master coordinates which are used to control the function of an output device, such as a display.
Free-hand creation of graphical objects by a user currently is supported by complicated devices having large drawing surfaces upon which the user moves a stylus or pen to draw an image. The drawing surface is related to the display surface by a dedicated applications process which maps the drawing surface to the display area. When the drawing is being made on the drawing surface, a conversion function is invoked, dispatching the application program, and converting the drawing into an image which is displayed on the screen of the display device.
The invention has the objective of providing a user with a graphics input device which permits the display device of a graphics processing system to be used like a drawing surface, without the need to provide a physical surface as an analog to the display surface. This permits a graphics processor system to provide to a user immediate feedback, or echoing, of a drawing operation which the user is conducting. Thus, the display screen of a CRT may be used much as a blank tablet upon which a user can draw.
The integrating graphics input device which has been invented by the applicants provides hand-to-eye feedback through a graphics processor system by combining cursor-like movement of a position area on a display surface, together with tablet-like entry of graphical image information by means of a stylus which can be manipulated by the user to draw within the located positioned area. The device can be used to enter a continuous image by successively relocating the position area in a sequence of overlapping positions within which the user's manual input is integrated to form a continuous, coherent image.
The closest prior art to this device is the inventor's integrating pointing device, described in U.S. Pat. No. 4,719,455 which is incorporated herein by reference. In that device, graphical input was provided by a hand-manipulated device which fit to the user's hand. In the device, gross and fine control of cursor position were generated, respectively, by a moveable cover and a moveable puck contained within the cover.